a1 Laboratory for Biochemical Parasitology, Department of Zoology, University of Glasgow, Glasgow G12 8QQ
a2 Electron Microscopy Centre, Department of Zoology, University of Glasgow, Glasgow G12 8QQ
A new method is described which has made possible the long-term axenic cultivation of Leishmania mexicana amastigotelike forms in Schneider's Drosophila medium supplemented with 2% (v/v) foetal calf serum. Unlike previous methods, it utilizes direct culture of parasites obtained from the lesions of infected animals rather than adaptation of promastigotes in vitro. Ultrastructural (possession of megasomes), biochemical (cysteine proteinase activity and gelatin SDS-PAGE banding pattern) and infectivity (in vivo) data are presented which show the close similarity of the cultured forms to lesion amastigotes. The axenically cultured forms grew optimally at a temperature of 32–33 °C, providing further evidence for their amastigote nature. It was found that adjustment of the pH of the growth medium to 5·4 was required in order to retain the amastigote morphology of the cultured parasites. This supports the notion that leishmanial amastigotes are acidophiles.
(Received November 01 1991)
(Revised February 26 1992)
(Accepted March 02 1992)